1. Technical Field
The present invention relates to a connected-screw driver adapted to drive screws, which are connected to a screw connecting belt, into a member to be tightened while feeding the screw connecting belt at a predetermined distance at a time in accordance with a screw tightening operation.
2. Description of Related Art
This kind of connected-screw driver is used for an operation for fixing by driving a gypsum board with a screw into a ground material, such as timber and a steel material. This connected-screw driver is provided with a screw feed mechanism for feeding the screw connecting belt a little by little in accordance with screw tightening operations. This screw feed mechanisms includes a cylindrical slider case fixed to a housing, a slider provided reciprocating movably in the slide case, a spring urging the slider toward a position away from the housing, and a drum rotated in accordance with the reciprocating movements of the slider so as to feed the screws intermittently.
When the driver body is pushed during a screw tightening operation with a front end thereof pressed against the member to be tightened, the bit and a screw, which are first separated from each other, come into engagement with each other, so that the screw comes off from the connecting belt due to the pressing force of the bit. The screw and bit are thereafter moved forward together, and the screw impinges upon the member to be tightened, to cause the same member to be tightened.
The behavior of the screw just coming off from the screw connecting belt is unstable, and the screw readily deviates from the bit until the screw impinges upon the member to be tightened. Consequently, in some cases, a screw-tightening position is shifted, or the screw is tightened diagonally.
Under the circumstances, various kinds of proposals to solve these problems have been made (refer to, for example, JP-A-57-061477 and JP-A-10-034553).
JP-A-57-061477 discloses a structure provided with a pair of spring-biased symmetrically formed chuck members, on which screws coming off from a strip (screw connecting belt) are retained.
JP-A-10-034553 discloses a structure provided on a feeder box (slider) with a stopper base, which engages with a member to be tightened, in such a manner that a position of the stopper base in the screw tightening direction can be varied, the structure being thereby capable of being operated for screws of various lengths.